Turbo-supercharger system having controlled inlet and exhaust waste gates



July 1o, 1951 2,559,623

TURBO-SUPERCHARGER SYSTEM HAVING CONTROLLED INLET G. I. HOLMES AND EXHAUST WASTE GATE Filed Feb 12, 1944 I\N u a in 0 2 m-L /O Flag. 2. 9 o I1 7 f/ 'sr/vauro@ /20 INVENTOR 6.2'. /ol. MES B Patented July l0, 1951 TURBO-SUPERCHARGER SYSTEM HAVING CONTROLLED INLET AND EXHAUST WASTE GATES Gifford I. Holmes, Garden City, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Application February 12, 1944, Serial No. 522,053

3 Claims. (Cl. 230-115) My invention relates to blower chargers and supercharger \systems for supplying gaseous or vaporized fuel to prime movers.

It is an object of the invention to provide an improved blower-charger system for a prime mover, and especially to provide an improved power plant for aircraft.

VAn object is to provide an improved system for charging an internal combustion engine with an exhaust-driven blower charger.

Another object is to provide methods and apparatus for preventing the stalling of aircraft engines at high altitudes at partially closed throttle.

Another object is to provide methods and apparatus to prevent over-heating and reduced engine efficiency of supercharged aircraft engines at relatively low altitudes.

Another object is to provide arrangements for overcoming the phenomena known as pumping or pressure pulsations in a turbo-blower for internal combustion engines.

A further object is to provide arrangements for maintaining airflow from an exhaust-driven blower.

Still another object is to provide an arrangement for bleeding suicient air to maintain reasonably uniform blower output pressure.

Another object is to provide arrangements for avoiding engine detonation caused by pulsation in intake pressure.

It is also an object to provide arrangements for permitting sudden opening or closing of the throttle of an engine without interfering with the proper operation of the engine either at high or low altitudes.

Still another object is to provide a two-stage blower system avoiding the need for variablespeed-change gearing.

Other and further objects and advantages will becomev apparent as the description proceeds.

It has been found that super-charged airplane engines actually produce less power at low altitude than at higher altitude, owing to the fact that the supercharger produces more intake pressure than necessary at low altitudes, where atmospheric pressure is a maximum, and it is necessary to throttle the intake to avoid overheating the engine. This throttling results in the waste of power by energy wasted in turbulence around the butterfly valve used as a throttle. The resultant excessive heating of the intake air may, in itself, be injurious.

Furthermore, particularly at high altitudes when an exhaust-driven blower-charger operates at high speed, or when the intake pipe of; the engine is partially throttled, cutting down the air ow from the blower, there is`a tendency for the blower to pump or cause pressure pulsation. It is desirable to avoid such pulsation in order to avoid ruining the engine by detonation. In addition it is necessary to avoid permitting such pressure pulsation to become great enough to produce a rarefaction travelling through the engine and the exhaust pipe, which leaves the exhaust turbine without any driving power and causes the blower-charger to stop, which in turn stalls the engine and prevents it from being restarted in rareiied upper altitude atmosphere.

It is accordingly an object of the invention to provide reliable, safe operation of a supercharged gas engine under all conditions of operation.

A more specific object of my invention is to provide means responsive to the pressure of the air from the exhaust turbine-driven blower and also responsive to Velocity pressure of either such intake air or the exhaust gases from the engine to control the supply of exhaust gases to the turbine in such a manner as to prevent surging.

It is also an object to provide means responsive to one or more of the foregoing conditions for operating a waste gate in the intake air supply line to the engine in such a manner as to prevent the creation of a high pressure condition.

It is also an object to provide means for improving the operation of the apparatus by providing means responsive to the turbine speed coordinated with the foregoing control means to eliminate turbine stalling.

In accordance with my invention in its preferred form, I utilize a power plant for an aircraft comprising an internal combustion engine with a rst stage blower driven by an exhaust turbine, and a second stage blower mechanically driven by the engine shaft. In the air line b.,- twen the first and second stage blowers I provide an opening leading to an air-Waste gate, and I provide a pressure control system preferably automatic which opens or closes the airwaste gate in accordance with variations in output pressure and output air velocity of the first stage blower in such a manner as to maintain a substantially fixed velocity head of the blower output. In this manner I obtain compensation for the eifect of', opening or closing the throttle of the engine which causes variations in the amount of air admitted to the engine. Furthermore, I may provide a delayed action control for reducing the speed of the exhaust-turbinedriven blower when intake air pressure becomes hi h.

better understanding of the invention will be afforded by the following detailed description considered in conjunction with theacccmpanylng drawings, in which:

Fig. l is a schematic diagram of an embodiment of the invention in which control apparatus is provided responsive to turbine speed and to velocity and total pressure of air from a first stage blower;

Fig. 2 is a fragmentary schematic diagram of apparatus employing means for controlling the supply of exhaust gas to a blower-driving turbine responsive to turbine speed and to the total pressure and velocity pressure of the exhaust gas.

Fig. 3 is a fragmentary diagram of a throttling arrangement controlling Waste gas supply to the turbine.

The apparatus illustrated in Fig. l comprises an internal combustion engine I with a second stage intake air-compressing blower 2 which is driven by the engine, a rst stage blower 3 and an exhaust gas turbine 4 for driving the blower 3. An exhaust pipe 5 is provided for connecting the engine and the turbine 4, and an air pipe 6 is provided for conveying the output of the rst stage blower 3 to the second stage blower 2.

An engine intake pipe 'I is provided for connecti ing the blower 2 to the engine I. For controlling the mixture and quantity of air and fuel supplied to the engine, a conventional throttle and carburetor 8 is provided which is connected in the air pipe 6 in the arrangement illustrated.

For preventing adverse effects on the blower 3 when the air intake at the engine is throttled down and enabling the blower output to be bled away, a waste connection 9 and a waste gate I0 may be provided in an air pipe 6. Preferably, a spring II, shown as a compression spring, is provided for normally biasing the waste gate ID to an open position.

For controlling the operation of the waste gate IIJ, a pressure motor I2 of the diaphragm type is provided having a static pressure connection I3 through a pipe I4 to the air pipe B and having a velocity pressure connection I5 to the air pipe S. The pipe I5 is in the form of a Pitot tube so that pressure supplied through it represents total pressure or the sum of static and velocity head in the pipe B. The arrangement is such that the pressure exerted on the diaphragm I6 by the air conveyed through the pipe I5 tends to close the air-waste gate IU, whereas equalization of the pressure on both sides of the diaphragm I6 permits the spring II to open the air-waste gate II).

Suitable means are provided for controlling the supply of exhaust gas to the turbine 4 in response to the pressure of the air in the air pipe 6 and also in response to the speed of the turbine 4. For speed limit control, a y-ball governor arrangement 20 is provided, and a link 2l is connected to the fly-ball governor 20 with a floating pivot 2l. For controlling the speed of exhaust turbine 4 in response to the position of the fly-ball governor 20, an exhaust gate 2`2 in a branch exhaust pipe 23 is connected to the link 2|.

For making the exhaust gate 22 responsive to the pressure in the pipe 5, a bellows arrangement 24 connected to the static pressure pipe I4 is provided and is arranged to control the position of the floating pivot 2 I of the exhaust gate operating link 2 I. In order to compensate for variations in 'barometric pressure when an aircraft is operated at different altitudes, a compensating bellows 25 is provided which is arranged to act inopposition to the intake air pressure bellows 25. The compensating bellows 25 may be lled with air to exert a substantially constant opposing force to the bellows 24 at all times, assuming a constant active pressure area of the bellows 24 and 25. For adjusting the eiect of the bellows 24, an adjusting screw 25a may be provided for the compensating bellows 25. In order to provide some damping in the eiect of the bellows 24 on the waste gate 22 and to provide delayed opening of the waste-gate 22 in the event of a sudden rise of pressure in the air pipe 6, and adjustable constriction 26 is preferably provided in the static pressure pipe I4 between the connections of the pipe I4 to the static tube I3 and to the bellows 24.

It will be understood that a suitable intercooler (not shown) may be included in the air pipe 6 between the two blower stages 3 and 2.

Under normal operating conditions, such as cruising conditions, when the engine I is being operated with full-open throttle or at such a throttle opening as to deliver a substantial fraction of its rated power, the velocity of the air intake in the pipe 6 is sufcient to create a velocity head overcoming the force of the biasing spring It, and, accordingly, the air-Waste gate Ill is kept closed by the pressure exerted on thei right-hand side of the diaphragm I6. However, in the event that the throttle 8 is suddenly closed or partially closed to such an extent as to cut down seriously the velocity of the intake air in the pipe 6 and to cause pumping or pressure surge to take place in the blower 3, the velocity pressure conveyed through the pipe l5 to the right-hand side of the diaphragm I6 falls off to a negligible value, and the pressure in the pressure motor I2 equalizes on either side of the diaphragm IB. This permits the spring Il to open the waste gate ID and relieve the output pressure of the rst stage blower 3 whereby its normal output ow is maintained and no surging or pumping takes place therein.

When the throttle 8 is suddenly closed, the pressure tends to rise suddenly in the pipe 6, but this circumstance does not directly affect the pressure motor I2, since the pressure rises on both sides of the diaphragm I6, and it is only the sudden lowering of the velocity head which permits the compression spring II to open the waste gate Ill. Owing to the existence of the constriction 26 in the pipe I4, the pressure motor I2 will act more quickly than the exhaust gate operating bellows 24. Consequently, the waste gate ID will be opened before the rise in pressure can cause the opening of the exhaust gate 22 and the consequent possible stalling of the exhaust turbine 4. Instead. the reduction in pressure in the static pipe I4 caused by the opening of the Waste gate I0 gradually causes contraction of the bellows 24 and a closing of the exhaust gate 22 to increase the proportion of exhaust gases admitted to the turbine 4 and thus counteracts the effect of the reduction in the total air and gases passing through the engine I. rlhe rate at which the exhaust gate 22 is closet' of course, determined by the flow of air through the constriction 26.

In the arrangement as just described, the airwaste gate I0 is normally closed during engine operation, and the exhaust gate 22 is normally partially throttled to maintain the air pressure in the pipe 6 at a suitable value by venting more or less of the exhaust gases to the atmosphere in order to control the speed oi' the first stage blower 3 driven by the exhaust turbine 4.

If desired, the control apparatus may be made responsive to the velocity pressure of the exhaust through the branch pipe 23 instead of the pipe 6. An arrangement embodying this feature is illustrated fragmentarily in Fig. 2.

The arrangement of Fig. 2 includes certain elements bearing the same reference characters as similar elements in Fig. 1 and certain other modified elements identied by reference characters represented by numerals having values one hundred greater than the reference characters identifying similar elements in Fig. 1.

In the arrangement of Fig. 2, a simple pressure relief valve I is provided which is spring biased to the closed position by a compression spring I I.

The strength of the spring is so chosen to vent the pipe 6 upon the occurrence of a dangerous excessive pressure,

In this case a pressure motor |I2 is provided which has a static pressure connection |I3 to the exhaust pipe |05 and a. Pitot-tube-type of total pressure connection I|5 to the exhaust pipe |05. A floating link I|6 is provided having an intermediate pivot ||6a connected to the diaphragm I6 of the pressure motor I |2 and about which the link |I6 is adapted to rock. One end of the link |I6 is connected to the iloating pivot |2I carried by the bellows |24 and |25, and a second link ||1 is provided connecting the opposite end of the link ||6 to the exhaust gate |22 through a spring-biased broken lever or knee linkage comprising elements |I0 and IIS. The knee linkage ||8, ||9 is so constructed that a spring ||9 normally holds it in the straight position, but the linkage is capable of being bent by movement of the center portion to the right against `the ten-A sion of the spring I I9.

For limiting maximum speed of the turbine 4, a generator type of governor |20 is provided which is mechanically connected to the turbine 4 and has electrically connected thereto a solenoid |2| carrying an extending rod |21 biased to the lefthand position by a spring |28. The rod |21 is so mounted that it is adapted to engage the knee linkage member |I9 when the solenoid |2| is strongly energized in response to high generator voltage resulting from excessive speed of the turbine 4.

When the velocity pressure in the exhaust pipe |05 falls, the pressure motor diaphragm |6 and the linkage I6 are moved to the left by the biasing spring IIS', carrying the link |I1 to the left and closing the exhaust waste gate |22.

When the air pressure in the air pipe 6 rises in response to throttling of the carburetor 8, for example, the bellows |24 rocks the link ||6 clockwise about the pivot ||6a to cause the exhaust waste gate |22 to be opened, whereupon less gas is supplied to the turbine 4, and the blower 3 will be slowed somewhat to cause reduction of air pressure in the pipe 6. As in the arrangement of Fig. l, a restriction |26 dampens the action of the high-pressure bellows |24. Consequently, when the velocity pressure of the exhaust gases falls sharply, the exhaust waste gate will be moved quickly toward the closed position, enabling a proportionally increasing amount of exhaust gases to be supplied to the turbine 4. When the throttle is suddenly closed. the static pressure in the air pipe 5 tends to rise sharply, but owing to the existence of the restriction 28, the velocity pressure-responsive motor |I2 acts toI correct for the condition before the high-pressure air will have had time to actuate the bellows pressure motor |24. Furthermore, the relief valve III operates to prevent excessive pressure in the pipe 6.

If the speed of the turbine 4 should exceed a predetermined upper limit, the rod |21 will be moved to the right against the tension of the spring |26 to break the knee link and rotate the arm I9 for opening the exhaust waste gate |22.

The adjustment screw a in Fig. 1, or |25a in Fig. 2 may be manipulated for altering the control point of the system as a whole. Such alteration of the control point varies the supply of air in the pipe 8 accordingly. It stands to reason that such alteration of the control point serves to control the power of the engine. Referring to Fig. l, adjustment of the screw 25a to move the fixed end of the bellows 25 downward opposes the action of the bellows 24 so as to re- Y quire higher static pressure in the bellows 24, and

therefore higher intake manifold pressure so as to increase the power of the engine.

If desired, the setting of the control point of the bellows arrangement 24, 25 maybe coordinated with the operation of the conventional carburetor and intake throttle 8 so as to utilize adjustment of the control point of the bellows arrangement 24, 25 for control of engine power or throttling when the intake air pressure is higher than atmospheric and permit the conventional throttling arrangement to be used for cutting down intake air to decrease engine power at low altitudes when the atmospheric pressure is substantially equal to sea-level pressure, and it may be necessary to hold a partial vacuum on the intake side of the engine in order to hold the fuel input down sufiiciently.

The butteriiy valve in the carburetor 8 may be biased to the full open position for minimum turbulence in the air stream passing therethrough whenever the air pressure required in the intake pipe is greater than atmospheric pressure. For example, as illustrated in Fig. 3, a link 3| may be provided interconnecting the bellows arrangement 24, 25 and a butterily-valve-controlling arm 34. The bellows 25 is secured by a pivot pin 32 to one end of the link 3| and the other end of the link 3| is secured by pivot pin 33 to a controlling arm 34 of the butterfly valve (not shown) in the carburetor 8a. The carburetor 0a is provided with a limit stop 35 at the"full open position of the butterfly-valve-controlling arm 34, and a relatively weak tension spring 36 is provided for closing the butterfly valve. The link 3| is mounted to rock about a pivot pin 31 mounted at the end of a push rod 38, the position of which is controlled by a throttle lever 33. For normallyl biasing the butterfly-valve-controlling arm 34 to the full open position, a relatively strong tension spring 4| is provided.

The arrangement of Fig. 3 is such that movement of the throttle lever 39 to the left increases engine power, and movement thereof to the right decreases engine power. Whenever high engine power is required so that the throttle 39 is moved to the left, or whenever atmospheric pressure is below sea level pressure, so that the bellows 25 tends to become distended, the relatively strong tension spring 4| overcomes the relatively weak tension spring 36 and moves the arm 34 against the limit stop 35 so that the butterfly valve in the carburetor 8a is wide open. Control of the engine power is then accomplished by movement pressure within the bellows 24, and consequently any position of the pivot pin 31 is such that the relatively strong spring 4I can overcome the relatively weak spring 36.

However, at low altitudes when the atmospheric pressure is substantially sea-level pressure, the external pressure balances the internal sealevel pressure within the bellows 25` and there is substantially no tendency for it to distend. The

action of the relatively strong spring Il is thus opposed. If then the throttle 39 is moved to the right for the purpose of reducing engine power, the link 3l pivots around the point 32 and causes the butterfly valve operating arm 3l to move to the right (the closing direction) in an amount determined by the position of the throttle arm 39, and enables sufficient pressure difference to be set up in the carburetor 8a to reduce the engine power suiliciently.

I have herein shown and particularly described certain embodiments of my invention and certain methods of operation embraced therein for the purpose of explaining its principle of operation and showing its application, but it will be obvious to those skilled in the art that many modifications and variations are possible, and I aim, therefore, to cover all such modifications and variations as fall within the scope of my invention which is dened in the appended claims.

What is claimed is:

1. A turbo-supercharger system comprising a blower adapted to deliver a supply of air under pressure, a first pipe connected to said blower and adapted to transport said supply of air, an exhaust gas driven turbine connected to drive said blower, a second pipe connected to said urbine and adapted to supply impelling exhaust gases to said turbine, a rst normally closed gate to the atmosphere in said first pipe, a second normally closed gate to the atmosphere in said second pipe, pressure-responsive means opera-Y tively connected to said first gate to open the same when the static pressure in said first pipe exceeds a predetermined limit, and pressure-responsive means operatively connected to said second gate to open the same when the static pressure in said rst pipe exceeds a predetermined limit.

2. A turbo-supercharger system comprising a blower adapted to deliver a supply of air under pressure, a first pipe connected to said blower and adapted to transport said supply of air, an exhaust gas driven turbine connected to drive said blower, a second pipe connected to said turbine and adapted to supply impelling exhaust gases to said turbine, a rst normally closed gat to the atmosphere in said rst pipe, a second normally closed gate to the atmosphere in said second pipe, pressure-responsive means operatively connected to said rst gate to open lthe same when the static pressure in said first pipe exceeds a predetermined limit, pressure-responsive means operatively connected to said second gate to open the same when the static pressure in said first pipe exceeds a predetermined limit, and pressure-responsive means operatively connected to said second gate to close the same as the velocity of the exhaust gases in the second pipe drops.

3. A turbo-supercharger system comprising a blower adapted to deliver a supply of air under pressure, a first pipe connected to said blower and adapted to transport said supply of air, an exhaust gas driven turbine connected to drive said blower, a second pipe connected to said turbine and adapted to supply impelling exhaust gases to said turbine, a nrst normally closed gate to the atmosphere in said rst pipe, a second normally closed gate to the atmosphere in said second pipe, pressure-responsive means operatively connected to said first gate to open the same as the velocity of the air in the rst pipe drops, and pressure-responsive means operatively connected to said second gate to open the same when the static pressure in the rst pipe exceeds a predetermined limit.

GIFFORD I. HOLMES.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,052,172 Rateau Feb. 4, 1913 1,110,864 Banner Sept. 15, 1914 1,154,959 Banner Sept. 28, 1915 1,240,531 Banner Sept.'18, 1917 1,265,444 Good May 7, 1918 1,310,683 Sherbondy July 22, 1919 1,346,564 Sherbondy July 13, 1920 2,283,175 Berger May 19, 1942 2,305,810 Muller Dec. 22, 1942 2,376,199 Shoults May 15, 1945 2,380,777 Moss July 3l, 1945 

